US2668658A - Centrifuge machine - Google Patents

Description

Feb. 9, 1954 A. PELTZER, SR 2,668,658

CENTRIFUGE MACHINE Filed March a, 1950 3 Sheets-Sheet 2 INVENTOR. berf Pe/fzer ,5),-

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f7 TTOENE v Feb. 9, 1954 PELTZER, 5 2,668,658

CCCCCCCCCCCCCCC NE Filed March 8, 1950 IN VEN TOR. A/ber/ Pe/fz er; 5/?

Patented Feb. 9, 1954 v i 1.} UNITED STATESRPATENT OFFICE CENTRIFUGE MACHINE Albert Peltzer, Sr., San Francisco, Calif., assignor to Merco Centrifugal (30., San Francisco, Calif.,

a corporation of California Application March 8, 1950, Serial No. 148,411

reasons, including particularly minimizing the possibility of plugging or clogging of the discharge nozzles. Such centrifuges have certain inherent difficulties, particularly in that the discharge from the rotor must be handled in such a manner as to avoid undue power loss, and care must be taken to avoid undue spillingof discharge material into portions of the housing where it is not desired, and splash-back of such spill against the fast running. rotor. Undue power consumption can be avoided to a substantial. degree by the use of backwardly reacting jets such as disclosed in Patents 1,847,751 and 2,060,239. Nozzles forming backwardly reacting jets will'not eliminate objectionable spill. even when the discharge from the nozzles is received by a volute such as disclosed in Patent 2,060,239.

- In addition to the foregoing it is frequently desirable to deliver the underflow material to a tank or other piece of equipment located a considerable'height above the centrifuge. The use of a'discharge volute such as disclosed in Patent 2,060,239 will develop a pressure head for discharge of the underflow'at an elevation above the. centrifuge, but in many instances greater pressure heads are desirable to facilitate discharge of the underflow to greater elevations. A. relatively high pressure head in the volute is also "desirable in that it facilitates operation at high underflow gravity, without causing clogging of the piping through which the underflow materia-I'may be conducted from the volute.

Because of the power losses which occur-in a centrifuge of the above character, considerable heating-takes place which in some instances may cause'iniury to heat sensitive material. Cooling means'in'corporated in the rotor construction is necessarily relatively complicated and expensive, and in general is'not satisfactory for most commeri'cal'applications. It is also desirable in some instancesfto regulate the temperature of the material. undergoing treatment, as for example to 5 Claims.- (Cl. 23321) maintain the material at an elevated temperature, or to maintain it at a relatively low or subnormal temperature. Here again the heat trans-- fer means used in the past have not been satisfactory for such continuous commercial machines.

It is an object of the present invention togenerally improve upon centrifuges and methods of the above character, particularly with respect to the means employed for receiving the discharge of underflow material.

It is another object of the invention to provide an improved centrifuge and method of. the above characterv having relatively efficient means for receiving the underfiow material discharged from the rotor, and which serves to develop a relatively high pressure. head for delivery of the underfiow material to any point desired.

Another object of the invention is toprovide an improved centrifuge of the above character having improved means for receiving and handling the underfiow material, and which facilitates the discharge of a high gravity underflow.

Another object of the invention is to provide a machine of the above character having improved means for receiving the underflow discharge whereby power consumption is reduced" and spill from the underfiow volute is minimized,

Another object of the invention is to provide an improved means and method for eifecting a heat transfer to or from the material being treated. whereby in the operation of the machine overheating can be prevented, or the material may be heated or cooledto a desired temperature level.

Additional objects and features of .theinven tion will appear from. the following description in which the preferred embodiment has been setforth in detail in conjunction with the accompanying drawing.

Referring to the drawing- Figure 1 is a side elevational view partly in section showing a machine incorporating the present invention.

Figure 2 is a diagrammatic plan view showing connection for the returnof discharge material to the rotor, for removal of discharge material and for introduction of washliquor.

Figure 3 is a sectional detail showing. the upper portion of the rotor and adjacent parts which provide. for the-discharge of overflow.

Figure 4 is a detail view in plan showing the so-called pickup ring at the lower end of the rotor section l0'c.

Figure 5 is a diagram schematically illustrating 3 the machine of Figure l and showing external connections for a return circuit which includes a vent box.

Figure 6 is a cross-sectional detail illustrating another embodiment of the invention.

Figure 7 is a cross-sectional detail taken alon the line 'I'I of Figure 6.

Figure 8 is a cross-sectional detail like Figure 6, illustrating another embodiment of theinvention.

Figure 9 is a. cross-sectional detail taken along the line 99 of Figure 8. V

Figure 10 is a schematic view illustrating connections to a centrifuge having heat exchange means such as illustrated in Figure 8.

Figure 11 is a cross-sectional detail similar to Figure 9 and illustrating an arrangement for draw-off of underflow material from between two adjacent vanes.

The centrifuge illustrated in the drawing consists generally of a rotor I carried by the vertical shaft II, and disposed within the'stationary housing I2. As will be presently described the rotor is provided with various passages, including a passage for inflow of fluid feed material, a passage for discharge of lighter centrifugally separated overflow, and a passage for introducing a supplemental fluid material which is preferably made up of the heavier centrifugally separated discharge material. Rotor shaft I I is connected by coupling I3 to the vertical shaft I4 of an electric motor I6. This motor is suitably supported upon a mounting ring I1 and carries the necessary bearings to maintain the rotor shaft in proper alignment. Ring I1 is carried upon the upper end of a supporting shell I8, which in turn is secured to the rotor housing I2. Ring I! is cushioned by the compression springs I9, and is retained against displacement by screws 2I.

Housing I2 is preferably made in a plurality of sections normally bolted together, and which when separated permit access to or removal of the rotor. Thus in the particular construction illustrated there are two main upper and lowerhousing sections I2a and I222 which form th space 24 for accommodating the rotor I0. Normally these sections are held together by screws 26 in conjunction with clamps 21.

The body of the rotor I0 is likewise preferably made of a number of annular parts including in this instance the main part IOa, and upper and. lower conical shaped parts I01) and I00. Part I0a has an inner portion 28 which is attached to the lower end of the rotor shaft II. Parts Illa and Iilb are retained together by suitable means such as the expansible clamping ring 29. Within the main chamber 36 of the rotor there is a group of spaced separating discs 3I such as are commonly used in centrifuges. Mountedwithin the outer peripheral wall of the main body part Illa, are the circumferentially spaced nozzles 32, each of which is provided with a discharge orifice 33 directed backwardly with respect to the direction of rotation. A suitable type of nozzl structure is disclosed in Patent 2,060,239.

Disposed inwardly of the set of discs 3| there is a sleeve-like member 34 which is downwardly divergent, and which has a lower flared portion 36 underlying the lowermost separating disc. The inner wall of member 34 is provided with circumferentially spaced vanes 31, and these vanes extend from the lower side of the flared portion 36. Member 34 forms a passage 38 for receiving fluid feed material, and this passage connects with the main chamber 30 through the passage 39 formed between flared portion 36, and the adjacent wall of portion 28.

The lower portion of the rotor forms an impeller M for the return of underflow material back into the rotor. Briefly this impeller is formed by the body part I00 which has an axial opening 42 in its lower end for receiving discharge underflow material. circumferentially spaced vanes 43 ar disposed within body part I60, and serve to impart rotational velocity to I material delivered into the impeller, with discharge of material through the radially extending passages 44 into the annular space 45 surrounding the outer portion of separating cham ber 36. Passages 44 are formed between the inner wall of body part la, and an inner conical shaped member 46. Walls or vanes 4 I are interposed between member 46 and the adjacent wall of body part Illa, whereby as the material passes through the passages 44 it must be at a rotational velocity approximating that of the rotor at the time of its discharge. The annular chamber portion 45 into which th material discharges from passages 44 is connected to the main separating chamber through the annular orifice 49.

The lower housing section I2!) is formed to provide a volute 5I, which is disposed generally in a plane at right angles to the axis of th rotor and substantially aligned withrthe plane of the nozzles 32. tially circular as viewed in plan, or it may be spirally contoured lik the volute of a centrifugal pump. It communicates withatangentialdis-I charge conduit 52. .In the arrangement shown in Figure 2 conduit 52 is connected to thepipe bend 53, which in turn connects with the fitting 54 at the bottom of the housing. Material rethe impeller 4| and a desired pressure head is maintained in the pipes 52, 53 and, in the volute5 I.

ure 2, the return can be by way of another piece of equipment, such as a flotation cell 6| (Figure 5). Pipe 62 is shown delivering material from the volute to the cell 6I, and from this cell material flows back by way of line 63 to the cen:

trifuge rotor. Line 64 represents a draw-off from flotation 'cell 6|, and line 65 represents in troduction of a wash liquor such as fresh water.

7 The fresh water is introduced in such a manner as to secure intimate mixing with the materia being returned by pipe 63. So-calledthroat rings 6'! and 68 are interposed between the nozzles 32 and the'volute passage 5|.

nular throat passage 69.

The outerportion of thethroat passage forms an annular orifice or passage II, through which the material passes from the throat to the volute passage 5I. The lower throat ring 68 can" The volute'passage can be substana Instead of providing a direct return as in Fig-I accuses 1 besloped downwardly from the nozzles 32 to the throatpassage it as illustrated, whereby when the machine is not in normal operation, any liquid received upon the throat ring 68 fromv nozzles 32 tends to flow by gravity into the volute passage 5.1. If desired the angle to which ring 68 is sloped may be increased beyond the angle shown.

When it is desired to repair or change the rotor, the upper housing section 12a. i released from the lower section, whereby itv can be lifted vertically together with the rotor to permit access to the working parts. For this purpose the inner edge 12 oi the throat ring 61 is slightly larger' in diameter than the diameter swept by the outer end of nozzles 32 thus permitting the nozzles to pass upwardly through the throat ring 61. To

extend the effective length of throat ring 61 inwardly, the upper housing section 12a is fitted an annular and inwardly faced recess '11. This recess is provided with a series of: circumierentially spaced vanes 15. Extending downwardly from. the top of the. housing there is a tube 18, having an outwardly turned or flared lower end portion '19, which is disposed within recess 11. Portion 19 includes the substantially parallel annular wall portions 8| and 82. Between these wall portionsrare the vanes 83 which deflect liquid inwardly and upwardly.

The lighter centrifugally separated overfiow discharges between vanes 83 and through the passage 84' into the chamber 85 from which it is withdrawn. Space 86 of the housing overlies chamber 85 and is in communication with, pas- S gev 38 and, the space 81 about member 34.

Previous reference has been made to the picking up of whatever small amount of the material may find its, way into the lower part of, the housing. Any material finding its way into the lower housing section I211 accumulates in, the annular space 88 surrounding the nozzle 56. The lower end of the impeller is provided with what can be termed a pick-up ring 9|, which, is in relatively close proximity with the upper end of nozzle 56. This pick-up ring is provided with arcuate vanes 92 (Figured) whereby any material finding its way intov space 88 is picked up by the action of ring 9t and, delivered back into the rotor together with the returned material. The vanes extend inwardly and are separated by slots 93.. Their leading portions 94 are bent downwardly to engage and urge fluid material upwardly.

To facilitate supplying a feed to the machine a conduit 90-15 mounted upon the upper housing section 12d and communicates with the upper. end of apassage 89 which is provided about the rotor shaft H and extends downwardly within member 34.. Within member 34 the shaft is shrouded by the sleeve 91. The feed material-can be receivedfrom a pipe 95 and screen 98.

Operation of my machine can be described as renews-rue rotor is driven ata suitable speed, such as the order of from 5,000 to.10,000 R. P. M. for a rotor having an inside diameter of 9 inches, to provide nozzle speeds which will vary in different instances but intypical instances will be of the order of 250 to 500 feet per second. The

fluid feed material employed will varyin different instances and may contain, for example one or more. suspended solids, with or without one or more components in solution or as a colloid. As.

1 an example of such feed material reference can be, made to starch liquor which contains finely divided starch particles in suspension. with solu ble carrying water, together with gluten. As this feed material is supplied, to the rotor heavier cen 1Q trifugally separated. material is discharged from ergy. As the discharging material impacts the the nozzles 32. and by virtue of the absolute velocity at the time of dischargethe jets of material pass outwardly through the throat passage 69 into the volute 51. With proper regulation of the discharge from volute 5!, the volute and the:

outer portion of the throatpassage 69 become filled with material, whereby a level is established which. may vary somewhat with operating condiq tions, but which. is intermediate the annular orifice H and the tips of the nozzles 32. As previously explained such regulation can be had by properly proportioning the passage through the orifice 56 whereby a predetermined pressure head is maintained in volute 5|, and, in the passages 52, 53. The material discharging from nozzles 33 is not in the form of solid, streams, but is in the form of jets of somewhat dispersed material, due probably to rotary movement (about the axis. of the orifices) as the. material passes through the discharge orifices. Although the backward direction of these jets serves torecover considerable kinetic energy and thus reduces the. power required for operation of the machine, the discharging material retains considerable kinetic ensurface of material in throat passage 69, a portion of this kinetic energy is used to keep the discharged slurry in violent agitation, and a. portion is transferred to the body of liquid material. As the result of such energy absorption the body of material in the throat passage has consider able rotary velocity in a direction about the axis of the rotor, and in addition there is a velocity component outwardly to cause flow through annularorifice H into the volute passage 51-. The rotary velocity component gradually decreases in a direction toward the throat orifice H to effect conversion of kinetic energy to static pressure head. In passing outwardly through the annular orifice H into the volute, passage 5| there is afurther reduction, infiow velocity in a. radial direction with the result thatthere is further build ing up, of a static pressure head in the volute. passage. Avery substantial pressure head. in. the volute passage is desirable because it enables better fiow from the. volute passage through the return pipe bend 53 back into the machine or through auxiliary equipment such as the fiotation cell 6| of Figure 5. In addition it permits discharge of the underfiow to a tank or; other piece of equipmentlocateda considerable height above the centrifuge.

In. addition to the above the throat passage 69 receives the discharging material in such a fashion as to minimize back splash upon the nozzles and upon the rotor. Elimination of back splash further reduces the power requirements for operation of the machine, and in addition it minimizes the amount of material which must be re-- turned back into the rotor for retreatment. It further reduces the possibili'tnr of centrifugally separated underfiow material finding its way into I the overflow. Swirling of material in throat pas- V sage B9 and also in the volute passage it is: de-

sirable in that. in; many instances it serves to retain materials in relatively .fluid condition, particularly .where the materials have tendencies similar to thixotropic characteristics such as tend the operation of the machine a novel method is employed. The material in the. throat passage 69 comprises a portion of a body of material, the

main part of which is in the volute chamber The portion of the liquid body which is in the throat passage 69 may be said to extend inwardly in a radial direction from the main part of the liquid body, and in this inwardly extending body portion the kinetic energy of underflow material received from the nozzles is converted to hydraulic or static pressure in the main part of the li uid bod In the e nbodiment of the invention illustrated in Figures 6 and 1, the throat rings NH and I02 are altered as to dimensioning to provide the throat passage I93. In addition, the rings have flared portions trant portion I06. This embodiment functions in substantially the same manner as the embodiment of Figure 1 except for the more desirable proportioning. v

Figures 8 and 9 illustrate a further embod1-, ment of the invention which incorporates heat exchange means. In this instance the two housing sections Ia and III?) can be constructed similar to the sections lid and I2!) of Figure '1, except that they are provided with annular flanges II2a, and M22). The parts H30, and 31), which can be formed of suitable material such as sheet metal, are mounted between the flanges II2a, H212, to form a restricted throat which is designated generally at II4. As viewed in plan the parts II3a, II3b are annularly contoured, and together with the flanges II2a, I IN), they form annular passages Ilfia, I Ifib for circulating a cooling or heating liquid. Surrounding the parts I I3a and I I3b, there is a volute part I II, which can likewise be fabricated of sheet metal, and which serves to form the volute passage I I8. A plurality of diifusion vanes II9 are positioned between the opposed faces of the parts I I3a, I Itb, and the spaces between these vanes form circumferentially spaced and outwardly divergent flow passages I2I. Because of the shaping and proportioning of these passages, the vanes serve to more efiiciently convey the material received from" the nozzles in a direction outwardly and into the volute passage H8. In so directing the material kinetic energy is more effectively and efficiently converted to hydraulic pressure, and splash-back is minimized. The inwardly faced walls of the parts II3a,' II3b are so curved as to form an 'inwardly divergent annular zone 122 for receiving material from the nozzles 32. The parts 311, I I3b'can be strengthened by providing a plurality of spaced ribs or webs I2 3a, I23b.

When using a construction as illustrated in Figures 8' and 9 the same return circuit and underflow draw-off connections can be employed as previously described with reference to Figure 2. However as indicated in Figure'll it is possible to provides. special underflow draw-01f which facilitates the draw-ofi of material at relatively high gravity. Thus in this connection two of the vanes II9a have adjacent ends which form an outwardly directed pocket I26, instead of one of the passages I2I. At the outer end of this pocket I05, I05 to form the enlarged en-' nozzle,'whereby such discharge' i inaterial isfdisthere is 'a passage I21 which connects to an derfiow draw-oil pipe. In a typical instance only. one such draw-01f pocket can be provided, and the remaining spaces between the vanes can be.

' passages of the type illustrated in Figure 9.

With the arrangement shown in Figure 11 it is possible to draw ofi starch at relatively high. gravity because of the static pressure head de-- veloped in the closed pocket I26 and'because under such pressure head-relatively high gravityunderflow material tends to flow without difficulty.

When using the starch draw-off shown in Fig- 1 ure 11 it is desirable to introduce wash water into-:= thereturn circuit by way of a tangential pipe I30, which should be locatedjust beyond the tangentialtake-off of the underflow return pipe. Introduction of wash in'this mannertends to have a lubricating action in the outer part of the volute passage and aids attainment of high un-' -sorbing or adding heat to the material being treated in the centrifuge. Thus in this instance a pump I28. is connected to a heat exchanger I29, I and to piping whereby liquid is withdrawn fromthe chambers I Ifia, IIfib, passed through the heat exchanger and then returned to these chambers; Eithercooling or heating liquid can be continu ously circulated through the chambers 6a,; H617, to effect an efiicient heat transfer with respect to material which is passing through thegeneral throat passage II4. By employing a suitable cooling liquid such as water, overh'eating of material having heat sensitive components can be avoided. By the use of a heated liquid, heat can be efiiciently transferred to the under-i. flow in order to maintain the material undergo ing treatment at a desired elevated temperature.- The ribs I23a and I231) can be made of goodheat conducting material to assist exchange of heat between walls II3a, II3b and the heat exchange liquid. Figure 10 also illustrates a starch draw-f oiT line I3I which leads from a closed pocket I 26 and which can be valve controlled. This application is a continuation-impartof my copending application Serial No. 584,879, filed; March 26, 1945, now abandoned. Iclaimz. 1. In a centrifuge, a rotor providedwith a pas-Q sage for introduction of feed material and also provided with nozzles forjdischarge of heavier"- separated material and alower part forming an' impeller to receive heavier. discharge material and to return the same to the rotor a housing, enclosing the rotor, means carried by the ,housejj. ing for receiving material discharged from-said, nozzles, a return nozzle at the lower end of'the housing and disposed beneath the'lower end of the impeller and directed upwardly into the' same, conduit means for returning a substan tialpart of the discharged: material to La charged upwardly into'the impeller, the housingbeing formed to provide a' space about'said'nozzle which is adapted to receive material whic'h-iri'ay spill into the housing jr g the rotor, and a impeller. and provided with vanes operating'insaid space to act upon material in said space to impelsuch material into the impeller.

; 2. In a centrifuge, a rotor arrangedto Operate one v rtica ax s and p ov d-with a p ssa e,

for introduction of feed material and also provided with nozzles for discharge of heavier separated material, and a lower portion forming an inverted conical shaped impeller to receive heavier discharge material and to return the same to the rotor, a housing enclosing the rotor, volute means carried by the housing for receiving material discharging from said nozzles, a nozzle at the lower end of the housing and directed to discharge material upwardly into the lower open end of the impeller, conduit means for returning a substantial part of the discharge material to said nozzle for introduction into the lower end of the impeller, the housing being formed to provide an annular space surrounding the nozzle which is adapted to receive material which may spil1 into the housing from the rotor, and a pick-up ring carried by the lower end of the impeller and operating in said recess, said pick-up ring having an opening aligned with the passage through said nozzle and being formed with vanes adapted to deliver material in said space into the impeller.

3. In a centrifuge, a rotor having a passage for introduction of feed material and havin circumferentially spaced nozzles for discharge of heavier separated material, a structure surrounding the rotor and formed to provide an annular volute passage, said volute passage being disposed generally in a plane at right angles to the axis of rotation of the rotor, and means interposed between the inner periphery of the annular volute passage and th periphery of the rotor forming an annular throat disposed to receive material from the discharge nozzles and serving to deliver such material into a mass of the heavier separated material occupying the annular volute passage, with conversion of kinetic energy to static pressure head, said throat providing an outwardly convergent entrant portion to receive material from the nozzles and a restricted portion through which such material passes from the entrant portion to the inner periphery of the volute passage, and a plurality of circumferentially spaced diifusion vanes disposed in said restricted portion and serving to direct material outwardly into the volute passage.

4. In a centrifuge, a rotor having a passage for introduction of feed material and having circumferentially spaced nozzles for discharge of heavier separated material, a structure surrounding the rotor and formed to provide an annular volute passage, said volute passage being disposed generally in a plane at right angles to the axis of rotation of the rotor, and means interposed between the inner periphery of the annular volute passage and the outer periphery of the rotor forming an annular throat disposed to receive material from the discharge nozzles and serving to deliver such material into a mass of the heavier separated material occupying the annular volute passage, said throat providing an outwardly convergent entrant portion to receive material from the nozzles and a restricted portion through which such material passes from the entrant portion to the inner periphery of the volute passage, a plurality of circumferentially spaced diffusion vanes disposed in said restricted portion and serving to direct material outwardly into the volute passage said throat together with said vanes forming means for converting kinetic energy of material discharging from the nozzle to static pressure head, and means for imposing a substantial pressure head on material in the volute passage to maintain the same and a portion of the annular throat filled with discharge material.

5. In a centrifuge, a rotor having a passage for introduction of feed material and having circumferentially spaced nozzles for discharge of heavier separated material, a structure surrounding the rotor and formed to provide an annular volute passage, said volute passage being disposed generally in a plane at right angles to the axis of rotation of the rotor, means interposed between the inner periphery of the annular volute passage and the outer periphery of the rotor forming an annular throat disposed to receive material from the discharge nozzles and serving to deliver such material into a mass of the heavier separated material occupying the annular volute passage, said throat providing an outwardly convergent entrant portion to receive material from the nozzles and a restricted portion through which such material passes from the entrant portion to the inner periphery of the volute passage, a plurality of circumferentially spaced diffusion vanes disposed in said restricted portion and serving to direct material through the spaces between said vanes, and from there into the volute passage, said throat together with said vanes forming means for converting kinetic energy of material discharging from the nozzles to static pressure head, the outer end of one space between two of said vanes being closed to the volute passage, means forming a passage for withdrawing underfiow material from th outer end of said last named space, whereby material so withdrawn is not delivered into the volute passage, means for imposing a substantial pressure head on material in the volute passage to maintain same and a portion of the annular throat filled with discharge material, and means forming a flow conducting path for continuously returning the major portion of the separated material from the volute passage back into the rotor for re-discharge through said nozzles, said last means including a flow passage communicating tangentially with said volute passage for removal of material therefrom.

ALBERT PELTZER, SR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,847,751 00.3 Mar. 1, 1932 1,923,454 Peltzer Aug. 22, 1933 1,945,786 Peltzer Feb. 6, 1934 2,013,668 Peltzer Sept. 10, 1935 2,060,239 Peltzer Nov. 10, 1936 2,534,210 Schutte Dec. 12, 1950

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